The present invention relates to systems and methods for tracking and navigating medical devices. More particularly, the invention relates to a method for tracking and navigating an interventional medical device while utilizing feedback signals generated by an array of electrical sensors on the interventional medical device.
In the medical arts, interventional medical devices, such as catheters or endoscopes, are frequently used to diagnose and treat various disorders in a patient, such as clogged or blocked blood vessels. An interventional medical device is introduced into a blood vessel of a patient by, for example, making an incision in the patient over the blood vessel and inserting the interventional medical device into the blood vessel of the patient. A interventional medical device operator such as a physician then maneuvers the interventional medical device through the blood vessels of the patient until the interventional medical device is properly situated to diagnose or treat the disorder. Similar techniques are used to insert interventional medical devices into other types of lumens within a patient.
In maneuvering the interventional medical device through the blood vessels or other lumens within the patient, there is a recurrent need to know the location of the interventional medical device within the body space of the patient. Conventional imaging systems create an image of the blood vessel or other lumen to provide 2- or 3-dimensional spatial relationships. If the position in three dimensions of the imaging head on the interventional medical device can be determined, then through use of three-dimensional imaging software, the relative positions and locations of the curves, twists, and turns, as well as the locations of the branch points, of the lumens can be determined. Knowing the positions allows a more accurate map of the patient to be created, which yields more effective diagnosis and treatment of the patient. For example, gathering accurate 3-D position data allows for an accurate blood flow map and consequent blood flow monitoring and modeling.
Traditionally, x-ray based technology, such as computed tomography (CT) has been used to provide a global roadmap of X-ray visible devices, showing their position within the patient. However, prolonged exposure to X-rays may be harmful to the patient, and it is therefore desirable to avoid such exposures.
In an effort to reduce radiation expose and not restrict access to the patient due to the patient being disposed within, for example, a CT gantry, 2-dimensional fluoroscopy is often used for interventional device tracking. Of course, 2-dimensional fluoroscopy suffers from a lack of information about the position of the device in a third dimension. To compensate for the lack of information in a third dimension, 2-dimensional fluoroscopy may be coupled with other tracking systems, such as magnetic tracking systems. Unfortunately, such systems are complex to implement because they require separate hardware, such as magnetic sensors associated with the interventional device and located at known positions external to the patient and, such systems must be coupled to the 2-dimensional fluoroscopy system to provide feedback in all three dimensions. At best, these systems are complex and can be inaccurate. Furthermore, they require repeated doses of ionizing radiation to update the 2-dimensional fluoroscopic data. Lastly, the device location must be registered with the anatomy, and magnetic trackers, for example, only provide absolute, and not relative position. Likewise, fluoroscopic images do not successfully image soft tissue, and so the registration system must rely heavily on preoperative data (e.g. from an angiogram) but anatomical features are prone to shift making this unreliable. Thus, these systems do not provide real-time feedback and require the continued exposure to ionizing radiation.
Thus, there is a need for a tracking system that can readily determine the location of a interventional medical device within a patient, relative to the relevant anatomy, without exposing the patient to harmful side effects, and that can be used with a wide variety of interventional medical devices or other imaging medical devices.